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Directed assembly of magnetic and semiconducting nanoparticles with tunable and synergistic functionality.
Scientific Reports ( IF 3.8 ) Pub Date : 2019-10-31 , DOI: 10.1038/s41598-019-52154-0
Mark Bartolo 1 , Jussi J Amaral 1 , Linda S Hirst 1 , Sayantani Ghosh 1
Affiliation  

The ability to fabricate new materials using nanomaterials as building blocks, and with meta functionalities, is one of the most intriguing possibilities in the area of materials design and synthesis. Semiconducting quantum dots (QDs) and magnetic nanoparticles (MNPs) are co-dispersed in a liquid crystalline (LC) matrix and directed to form self-similar assemblies by leveraging the host's thermotropic phase transition. These co-assemblies, comprising 6 nm CdSe/ZnS QDs and 5-20 nm Fe3O4 MNPs, bridge nano- to micron length scales, and can be modulated in situ by applied magnetic fields <250 mT, resulting in an enhancement of QD photoluminescence (PL). This effect is reversible in co-assemblies with 5 and 10 nm MNPs but demonstrates hysteresis in those with 20 nm MNPs. Transmission electron microscopy (TEM) and energy dispersive spectroscopy reveal that at the nanoscale, while the QDs are densely packed into the center of the co-assemblies, the MNPs are relatively uniformly dispersed through the cluster volume. Using Lorentz TEM, it is observed that MNPs suspended in LC rotate to align with the applied field, which is attributed to be the cause of the observed PL increase at the micro-scale. This study highlights the critical role of correlating multiscale spectroscopy and microscopy characterization in order to clarify how interactions at the nanoscale manifest in microscale functionality.

中文翻译:

具有可调和协同功能的磁性和半导体纳米粒子的定向组装。

在材料设计和合成领域中,使用纳米材料作为构建基块并具有超常功能来制造新材料的能力是最吸引人的可能性之一。半导体量子点(QDs)和磁性纳米颗粒(MNPs)共分散在液晶(LC)矩阵中,并通过利用主体的热致相变定向形成自相似的组装体。这些共装配体包括6 nm CdSe / ZnS QD和5-20 nm Fe3O4 MNP,桥接纳米级至微米级的长度标度,并且可以通过<250 mT的施加磁场进行原位调制,从而增强QD光致发光( PL)。在5和10 nm MNP的共同装配中,这种效应是可逆的,但在20 nm MNP的装配中却显示出滞后现象。透射电子显微镜(TEM)和能量色散光谱显示,在纳米级,尽管量子点被密集堆积在组件的中心,但MNP相对均匀地分散在整个簇中。使用Lorentz TEM,观察到悬浮在LC中的MNP旋转以与所施加的电场对齐,这归因于所观察到的PL在微尺度上增加。这项研究强调了关联多尺度光谱学和显微镜表征的关键作用,以阐明纳米尺度上的相互作用如何体现在微观尺度的功能上。观察到悬浮在LC中的MNP旋转以与外加电场对齐,这归因于所观察到的PL在微尺度上增加。这项研究强调了关联多尺度光谱学和显微镜表征的关键作用,以阐明纳米尺度上的相互作用如何体现在微观尺度的功能上。观察到悬浮在LC中的MNP旋转以与外加电场对齐,这归因于所观察到的PL在微尺度上增加。这项研究强调了关联多尺度光谱学和显微镜表征的关键作用,以阐明纳米尺度上的相互作用如何体现在微观尺度的功能上。
更新日期:2019-11-01
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